There is definitive evidencde from from multiple randomized trials that trans-fatty acids (TFA) have adverse health effects. - GreenMedInfo Summary

We presently have definitive evidence from multiple randomized trials that trans-fatty acids (TFA) have adverse effects on blood lipids, near definitive evidence that TFA increase inflammatory markers in blood, and strong evidence from prospective epidemiologic studies that high TFA intake is associated elevated risks of coronary heart disease. Food additives should be allowed to be used only if there is reasonable certainty of no harm. Thus, the present US Food and Drug Administration position of allowing TFA in the food supply is indefensible, and large numbers of Americans are dying prematurely because of its failure to act to responsibly.